When a self emulsification type oily liquid cosmetic composition contacts with water, phase reversal of emulsion occurs to produce an oil-in-water type emulsion, and typical examples of the self emulsification type oily liquid cosmetic composition include a cleansing cosmetic composition, a bath cosmetic composition, and the like.
It has recently been required for a makeup cosmetic to attain a long wear for makeup and also tendency such as heavy makeup increases in accordance with a trend. Therefore, it is required to develop a cleansing cosmetic composition having strong detergency for the purpose of removing makeup cosmetic compositions containing an oily component as a base, such as foundation and lipstick.
The cleansing cosmetic compositions in various preparation forms are on the market and examples thereof include water-based cleansing cosmetic composition, oil-based cleansing cosmetic composition, polyhydric alcohol-based cleansing cosmetic composition, and liquid crystal-based cleansing cosmetic composition containing a surfactant in the preparation forms such as liquid, gel and cream. Among these cleansing cosmetic compositions, it is known that an oily liquid cleansing cosmetic composition is excellent in compatibility with an oily component of a cosmetic and is therefore most excellent in detergency. Consequently, a product (cleansing cosmetic composition), which is most popular on the market, is a self emulsification type oily product including a mixture of an oily component and a surfactant. This product has a property such that phase inversion quickly occurs when contacted with water. At first, stains are migrated (dissolved) in the oily component by applying the cleansing cosmetic composition well to makeup stains. And then, the cleansing cosmetic composition is contacted with water to produce an oil-in-water type emulsion of the oily component containing stains, and thus makeup stains can be removed by washing out with water.
The self emulsification type oily liquid cosmetic composition must contain a high concentration such as 8 to 30% by mass of a surfactant so as to quickly self-emulsify when contacted with water. Examples of a conventional surfactant used in the self emulsification type oily liquid cosmetic composition include polyoxyethylene sorbitan branched fatty acid ester, polyethylene glycol branched fatty acid ester and polyoxyethylene branched alkyl ether. Among these surfactants, it has conventionally been known that a polyoxyethylene-based surfactant has some safety concerns. When a self emulsification type oily liquid cleansing cosmetic composition containing a high concentration of this polyoxyethylene-based surfactant is directly applied on the skin, there may arise problems such as strong creaky feel after cleansing and skin trouble, and thus there is some safety concerns. The polyoxyethylene-based surfactant has a problem such that it gives drastically poor taste and smell in the mouth. Therefore, with regard to the cleansing cosmetic composition which sometimes penetrates into the mouth when used in the face portion, especially when used to remove lipstick, users feel drastic discomfort.
To solve the problem of the cosmetic composition using the polyoxyethylene-based surfactant, for example, Japanese Unexamined Patent Application, First Publication No. Sho 58-185537 discloses a cosmetic composition using a polyglycerin fatty acid ester.
A surfactant which has high safety and is free from discomfort flavor and is also commonly used in foods includes, for example, a polyglycerin fatty acid ester. However, most polyglycerin fatty acid esters on the market are not easily dissolved in an oily component. Even when dissolved in the oily component, there arises a problem that the compositions are not self-emulsified because of poor dispersibility in water. Therefore, a self emulsification type oily cleansing cosmetic composition including the polyglycerin fatty acid ester and the oily component is inferior in storage stability of the product (cleansing cosmetic composition) because of poor solubility (not easily dissolved in the oily component). Alternatively, stains can not be washed out because of poor dispersibility in water, and the oily component is remained on the skin, resulting in strong greasy feel. Therefore, in the self emulsification type oily cleansing cosmetic composition, the polyglycerin fatty acid ester was merely used as an auxiliary emulsifier.
A conventional self emulsification type oily liquid cleansing cosmetic composition had a problem that, in case of cleansing hard-to-remove cosmetic compositions such as heavy-coated foundation and mascara containing oil-resistant and water-resistant components, the skin tends to be rubbed strongly during a process of applying the cleansing cosmetic composition to these hard-to-remove cosmetic compositions to raise makeup stains, and thus causing problems such as skin trouble and eyelash removal. In a next process of self-emulsifying by contacting with water, the cleansing cosmetic composition becomes a liquid crystal and a white gel-like material, and then is dispersed in water. However, the cleansing cosmetic composition is not quickly dispersed in water and is therefore remained on the skin to give long-term slimy feel, and also rinsing requires a long time.
By the way, a bath cosmetic composition is often used during bathing so as to prevent skin irritations, cracks and chaps and to improve skin conditions. Examples of the preparation form of the bath cosmetic composition include bath salt, bath oil and herbal medicine. Among these, with regard to a product of a self emulsification type oily bath oil including a mixture of an oily component and a surfactant, when the bath oil is put into bath water, the bath oil is self-emulsified in bath water and the oily component in the form of fine particles is uniformly dispersed in bath water. Thus there can be expected various improving effects peculiar to the oily component, for example, emollient, moisturizing, anti-inflammatory and warm bathing effects.
However, a conventional self emulsification type oily bath cosmetic composition including a mixture of an oily component and a surfactant is insufficient in dispersibility in bath water and is not self-emulsified, and is therefore floated in the preparation form of a bath cosmetic composition. Consequently, the bath cosmetic composition gives greasy feel to cause problems such as poor skin sensation after bathing and adhesion of the bath cosmetic composition onto a bath wall.
For the same reason as in case of the cleansing cosmetic composition, the polyglycerin fatty acid ester is not substantially used as the surfactant of the self emulsification type oily bath cosmetic composition. Even when used, the polyglycerin fatty acid ester was merely used as an auxiliary emulsifier.
An object of the present invention is to solve the problems described above and to provide a self emulsification type oily liquid cosmetic composition which ensures safety for the human body and is excellent in storage stability, and is also excellent in dispersibility in water due to easy self emulsification and is excellent in tactile sensation.